Analysis for metallothioneins using coupled techniques

Analytical chemistry of metallothioneins based on the coupling of a high resolution separation technique with an element or species selective detection technique is discussed. The role of size-exclusion chromatography (SEC) with on-line atomic spectrometric detection for the quantification of metallothionein fraction in cell cytosols is evaluated. Particular attention is given to the conditions for the separation of metallated metallothionein isoforms (MT-1, MT-2, MT-3) and sub-isoforms within these classes by anion-exchange and reversed-phase HPLC. Techniques for interfacing chromatography with atomic absorption spectrometry (AAS), inductively coupled plasma atomic emission spectrometry (ICP AES) and ICP mass spectrometry (MS) are assessed. The potential of electrospray (tandem) mass spectrometry for the characterization of metallothionein isoforms with respect to molecular mass and aminoacid sequence is highlighted. Perspectives for capillary zone electrophoresis (CZE), microbore and capillary HPLC with ICP MS and electrospray MS(/MS) detection for the probing of metallothioneins are discussed. Applications of hyphenated techniques to the analysis of real-world samples are reviewed.